Fuchsia: Generate SSH credentials for device boots.

This fixes a bug in the runner scripts which prevented SSH cred
generation for device boots, but allowed emulator run credentials to
be re-used. The issue only manifested on clean builds with no prior
emu runs.

Bug: 899285
Change-Id: Icfb2b734bf527b44cb671b08ee7d21563ae82a8c
Reviewed-on: https://chromium-review.googlesource.com/c/1355850Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612839}

build/fuchsia/boot_data.py

@@ -40,14 +40,19 @@ def _TargetCpuToSdkBinPath(target_arch):
   return os.path.join(common.SDK_ROOT, 'target', target_arch)
 
 
-def _ProvisionSSH(output_dir):
-  """Generates a keypair and configuration data for the SSH client.
-  Returns a path to the client public key."""
+def _GetPubKeyPath(output_dir):
+  """Returns a path to the generated SSH public key."""
+
+  return os.path.join(output_dir, 'id_ed25519.pub')
+
+
+def ProvisionSSH(output_dir):
+  """Generates a keypair and config file for SSH."""
 
   host_key_path = os.path.join(output_dir, 'ssh_key')
   host_pubkey_path = host_key_path + '.pub'
   id_key_path = os.path.join(output_dir, 'id_ed25519')
-  id_pubkey_path = id_key_path + '.pub'
+  id_pubkey_path = _GetPubKeyPath(output_dir)
   known_hosts_path = os.path.join(output_dir, 'known_hosts')
   ssh_config_path = os.path.join(output_dir, 'ssh_config')
 
@@ -68,8 +73,6 @@ def _ProvisionSSH(output_dir):
   if os.path.exists(known_hosts_path):
     os.remove(known_hosts_path)
 
-  return id_pubkey_path
-
 
 def _MakeQcowDisk(output_dir, disk_path):
   """Creates a QEMU copy-on-write version of |disk_path| in the output
@@ -98,7 +101,8 @@ def GetBootImage(output_dir, target_arch):
   """"Gets a path to the Zircon boot image, with the SSH client public key
   added."""
 
-  pubkey_path = _ProvisionSSH(output_dir)
+  ProvisionSSH(output_dir)
+  pubkey_path = _GetPubKeyPath(output_dir)
   zbi_tool = os.path.join(common.SDK_ROOT, 'tools', 'zbi')
   image_source_path = GetTargetFile(target_arch, 'fuchsia.zbi')
   image_dest_path = os.path.join(output_dir, 'gen', 'fuchsia-with-keys.zbi')

build/fuchsia/device_target.py

@@ -45,8 +45,8 @@ class DeviceTarget(target.Target):
     self._loglistener = None
 
     if self._auto:
-      self._ssh_config_path = EnsurePathExists(
-          boot_data.GetSSHConfigPath(output_dir))
+      boot_data.ProvisionSSH(output_dir)
+      self._ssh_config_path = boot_data.GetSSHConfigPath(output_dir)
     else:
       self._ssh_config_path = os.path.expanduser(ssh_config)
       self._host = host